Numerical Modelling of CO₂ Injection and Trapping Mechanisms in Depleted Gas Reservoirs

Abstract

Depleted gas reservoirs offer significant potential for permanent carbon dioxide (CO₂) storage while supporting enhanced gas recovery. However, predicting CO₂ migration and long-term containment requires robust numerical modelling of multiphase flow, reservoir heterogeneity, and trapping processes. This study examines the application of numerical modelling to CO₂ injection and trapping mechanisms in depleted gas reservoirs, focusing on structural, residual, solubility, and mineral trapping.
Numerical simulation provides a framework for evaluating CO₂ plume evolution, pressure distribution, injectivity, storage efficiency, and potential leakage pathways under varying reservoir conditions. Particular attention is given to reactive transport and long-term performance prediction, which are essential for understanding changes in reservoir properties and CO₂ behaviour over extended storage periods. The study further considers the influence of residual gas saturation, geological heterogeneity, permeability, porosity, and injection conditions on storage performance. Integrating multiphase-flow and reactive-transport modelling can improve prediction of CO₂ retention, enhance storage efficiency, and support safer and more reliable geological carbon storage in depleted gas reservoirs.